HOW TO: Use a Snatch Block When Winching
Learning how to use a snatch block, also known as a pulley block, is an essential vehicle recovery skill for off-roading and overlanding. A snatch block is a heavy-duty pulley inside a metal casing that is used with a winch to recover a stuck vehicle.
Purpose of Snatch Blocks
Snatch blocks can serve two purposes in off-road vehicle recovery:
Increasing the pulling force of a winch
Redirecting the force of the winch cable to pull the stuck vehicle from a variety of angles.
This versatility extends the capabilities of your winch, allowing for recovery of heavier or seriously stuck vehicles or rescues in challenging circumstances.
Modern snatch blocks used for vehicle recovery in overlanding and off-roading are simple devices, including a pulley (also known as a sheave) sandwiched between two metal side plates and held together with a pin. The side plates can be twisted apart to wrap the winch line around the pulley. When the side plates are lined up, the two holes form an eye that is used to attach the snatch block to an anchor or vehicle using shackles and (in some cases) tree savers or other recovery straps.
Common Techniques for using Snatch Blocks
Snatch Blocks can be used in a number of different scenarios and configurations in off-road recovery. Here, we will cover several common techniques.
The physics of using winch snatch blocks can be a bit counterintuitive, but we will try to explain where it is easy to make errors in these common scenarios.
A snatch block bolsters the pulling force of the winch by supplying mechanical advantage, a function of passing the winch cable around the snatch block’s pulley and back to the vehicle. The snatch block is used to double the pulling force exerted by the winch in a self-recovery situation where a tree is used as an anchor. It is not quite double the force, because of friction added by the snatch block itself. The winch cable extends from the winch on the vehicle through the snatch block and back to a secure recovery point on the vehicle. While the snatch block reduces the pulling force required by the winch in this configuration, note that the anchor (the truck in this case) is still bearing the entire load of the vehicle. This is one of the most common recovery techniques with a winch and snatch block.
You could anchor directly to the tree-saver with a recovery shackle instead of a snatch block but using the snatch block has the advantage of reducing the strain on your winch. Here is a tricky nuance to the physics. If the end of the winch cable attached back to a tree instead of the vehicle, as pictured, the snatch block supplies no mechanical advantage. Since the line is static between the trees, the winch would be needed to pull the full load of the vehicle. This is the same as attaching directly to the tree-saver with no snatch block involved.
Another common technique involves two vehicles where one vehicle is stuck and the other uses its winch to rescue it.The snatch block is connected to the stuck vehicle with a shackle at a sturdy recovery point. The winch cable runs from the recovery vehicle through the shackle on the stuck vehicle, then connects back to the recovery vehicle with a shackle at a recovery point.
Using Multiple Snatch Blocks
Multiple snatch blocks can be used in a winching and pulley configuration to further increase the pulling power of the winch.
Such is the case below, where a second snatch block is attached to the rescue vehicle and the cable passes through it and back to the stuck vehicle. This triples the pulling power of the winch. This technique can be helpful when the stuck vehicle’s weight exceeds the ability of the winch or extra force is needed to pull a very stuck vehicle loose.
Using a Snatch Block to redirect force to another vehicle
Sometimes it is difficult or impossible to use a rescue vehicle winch to pull directly on a stuck vehicle. In such cases, a snatch block can redirect the force coming from the rescue vehicle to pull the stuck vehicle in the ideal direction. a tree is used as an anchor so that the rescue vehicle can exert pulling force on the stuck vehicle at a 90-degree angle. In this winching configuration, the snatch block is attached to a tree saver strap with a shackle to prevent damage to the tree. In place of the tree, another large object, could be used, such as a secure boulder. In this case, the snatch block does not reduce the force required by the winch to pull the stuck vehicle – there is no mechanical advantage.
As was explained above, you should always use a tree saver to connect your winch line to a tree or rock to prevent damage to both your anchor and your winch line.
Use of Shackles and Load Limits
When you are using a snatch block to gain a mechanical advantage or redirect the winch line, use a shackle to connect the snatch block to the tree saver. Thread the winch line around the snatch block sheave before connecting it to the shackle. Only use rated shackles, the manufacture lists the working load limit (WLL) of the shackle. On metal shackles, the WLL on rated will be embossed on the side. If you are using a synthetic shackle, make sure you know its load limit. The working load limit is the maximum weight that a particular piece of rigging should be used to manage under normal conditions. The breaking strength rating (different from the WLL) is the weight at which a shackle can be expected to fail. The breaking strength is typically three times the WLL. Do not side load your D-ring shackle (see image), as this is not how it is designed to be used and weakens it. Also, make sure your shackle pin is screwed all the way to the end. It only needs to be lightly hand tightened but should be all the way in.
Check out this video from Ordealist that helps explain all about Snatch Blocks
Using a snatch block with a winch for off-road recovery
by: Ordealist
Desert Wranglers is not affiliated with or is sponsored by Ordealist, or gear america. This video is for instructional purposes only.